In the prior art, a boundary of a work area may be defined by a buried wire, a cable, or conductor associated with an applied current (e.g., an alternating current). A vehicle for operation in the work area is equipped with a magnetic field detector or an electric field detector for detecting the magnetic or electric field generated by the boundary wire, cable, or conductor. If a magnetic or electric field is detected, a vehicle controller may instruct the vehicle to change its course to some random path within the work area. However, if the vehicle is a mower, sprayer, or other device that is designed to cover all or a substantial portion of the work area, the execution of such random paths tends to be slow and energy inefficient. Thus, there is a need for an alternative method and system for determining the position of the vehicle.